Potential Feedbacks Between Pacific Ocean Ecosystems and Interdecadal Climate Variations

Miller, Arthur J.; Alexander, Michael A.; Boer, G. J.; Chai, Fei; Denman, Kenneth L.; Erickson, D. J.; Frouin, Robert; Gabric, Albert Jerome; Laws, Edward A.; Lewis, Marlon R.; Liu, Zhengyu; Murtugudde, Ragu; Nakamoto, S.; Neilson, Douglas J.; Norris, Joel R.; Ohlmann, J. Carter; Perry, R. Ian; Schneider, Niklas; Shell, Karen M.; Timmermann, Axel

doi:10.1175/bams-84-5-617

Cited by 55 publications

(32 citation statements)

References 102 publications

(88 reference statements)

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“…All of these studies come to the conclusion that phytoplankton are an important component in the surface layer heat budget of the tropical oceans. A recent review study of Miller et al (2003) provides more details on possible biophysical feedbacks in the Pacific Ocean.…”

Section: Summary and Discussionmentioning

confidence: 99%

Biophysical Feedbacks in the Tropical Pacific

Marzeion¹,

Timmermann²,

Murtugudde

et al. 2005

Journal of Climate

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This study explores the influence of phytoplankton on the tropical Pacific heat budget. A hybrid coupled model for the tropical Pacific that is based on a primitive equation reduced-gravity multilayer ocean model, a dynamic ocean mixed layer, an atmospheric mixed layer, and a statistical atmosphere is used. The statistical atmosphere relates deviations of the sea surface temperature from its mean to wind stress anomalies and allows for the rectification of the annual cycle and the El Niño-Southern Oscillation (ENSO) phenomenon through the positive Bjerknes feedback. Furthermore, a nine-component ecosystem model is coupled to the physical variables of the ocean. The simulated chlorophyll concentrations can feed back onto the ocean heat budget by their optical properties, which modify solar light absorption in the surface layers. It is shown that both the surface layer concentration as well as the vertical profile of chlorophyll have a significant effect on the simulated mean state, the tropical annual cycle, and ENSO. This study supports a previously suggested hypothesis (Timmermann and Jin) that predicts an influence of phytoplankton concentration of the tropical Pacific climate mean state and its variability. The bioclimate feedback diagnosed here works as follows: Maxima in the subsurface chlorophyll concentrations lead to an enhanced subsurface warming due to the absorption of photosynthetically available shortwave radiation. This warming triggers a deepening of the mixed layer in the eastern equatorial Pacific and eventually a reduction of the surface ocean currents (Murtugudde et al.). The weakened south-equatorial current generates an eastern Pacific surface warming, which is strongly enhanced by the Bjerknes feedback. Because of the deepening of the mixed layer, the strength of the simulated annual cycle is also diminished. This in turn leads to an increase in ENSO variability.

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Section: Summary and Discussionmentioning

confidence: 99%

Biophysical Feedbacks in the Tropical Pacific

Marzeion¹,

Timmermann²,

Murtugudde

et al. 2005

Journal of Climate

Self Cite

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“…This is not generally the case ( Fig. 2; see also Ohlmann et al 1996) and, especially at midlatitudes in summer or in the equatorial and tropical upwelling systems, its impact, which depends also on water turbidity (Mobley 1994), is not negligible (e.g., Miller et al 2003;Marzeion et al 2005). Therefore, we also include that effect in the diagnostics of dianeutral fluxes presented here.…”

Section: Introductionmentioning

confidence: 99%

Water-Mass Transformations in a Neutral Density Framework and the Key Role of Light Penetration

Iudicone

Madec

McDougall

2008

Journal of Physical Oceanography

100

147

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A new formulation is proposed for the evaluation of the dianeutral transport in the ocean. The method represents an extension of the classical diagnostic approach for estimating the water-mass formation from the buoyancy balance. The inclusion of internal sources such as the penetrative solar shortwave radiation (i.e., depth-dependent heat transfer) in the estimate of surface buoyancy fluxes has a significant impact in several oceanic regions, and the former simplified formulation can lead to a 100% error in the estimate of water-mass formation due to surface buoyancy fluxes. Furthermore, internal mixing can also be overestimated in inversions of in situ data when the shortwave radiation is not allowed to be penetrative.The method examines the evolution equation of neutral density via the tendencies of potential temperature and salinity. The neutral density framework does not require the choice of a reference pressure and thus, unlike previous approaches that consider potential density, it is well suited for examining the whole open-ocean water column.The methodology is easy to implement, particularly for ocean numerical models. The authors present here its application to a long simulation made with an ice-ocean global model, which allowed the method to be validated.

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“…Ocean turbidity through depthdependent attenuation of solar radiation is also investigated in a bulk-type mixed layer model by Kara et al (2004). Potential influences of phytoplankton in the Pacific on long-term climate variations are discussed by Miller et al (2003).…”

Section: Introductionmentioning

confidence: 99%

Effects of Ocean Biology on the Penetrative Radiation in a Coupled Climate Model

et al. 2006

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The influence of phytoplankton on the seasonal cycle and the mean global climate is investigated in a fully coupled climate model. The control experiment uses a fixed attenuation depth for shortwave radiation, while the attenuation depth in the experiment with biology is derived from phytoplankton concentrations simulated with a marine biogeochemical model coupled online to the ocean model. Some of the changes in the upper ocean are similar to the results from previous studies that did not use interactive atmospheres, for example, amplification of the seasonal cycle; warming in upwelling regions, such as the equatorial Pacific and the Arabian Sea; and reduction in sea ice cover in the high latitudes. In addition, positive feedbacks within the climate system cause a global shift of the seasonal cycle. The onset of spring is about 2 weeks earlier, which results in a more realistic representation of the seasons. Feedback mechanisms, such as increased wind stress and changes in the shortwave radiation, lead to significant warming in the midlatitudes in summer and to seasonal modifications of the overall warming in the equatorial Pacific. Temperature changes also occur over land where they are sometimes even larger than over the ocean. In the equatorial Pacific, the strength of interannual SST variability is reduced by about 10%-15% and phase locking to the annual cycle is improved. The ENSO spectral peak is broader than in the experiment without biology and the dominant ENSO period is increased to around 5 yr. Also the skewness of ENSO variability is slightly improved. All of these changes lead to the conclusion that the influence of marine biology on the radiative budget of the upper ocean should be considered in detailed simulations of the earth's climate.

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Potential Feedbacks Between Pacific Ocean Ecosystems and Interdecadal Climate Variations

Cited by 55 publications

References 102 publications

Biophysical Feedbacks in the Tropical Pacific

Biophysical Feedbacks in the Tropical Pacific

Water-Mass Transformations in a Neutral Density Framework and the Key Role of Light Penetration

Effects of Ocean Biology on the Penetrative Radiation in a Coupled Climate Model

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